Motor seals

ABSTRACT

A submersible motor comprising a first housing including a motor and a second housing enclosing electrical connections between the motor and a jacketed electrical cord to the second housing. The first housing has a cavity therein in the periphery thereof. A body of compressible resilient elastomeric material is positioned in the cavity and has an exterior configuration and dimensions which conform generally with the configuration and dimensions of the cavity. The body has a plurality of generally axial passages therein through which the magnet wires from the motor extend. The wires have a diameter so that they can be readily inserted through the passages in the body. The second housing has an annular wall extending axially through the open end of the cavity in the first housing and operable, when the second housing is in mounted position on the first housing, to compress the body radially into tight conformity with the wires from the motor.

This invention relates to submersible motors and particularly to sealsfor submersible motors.

BACKGROUND AND SUMMARY OF THE INVENTION

In submersible electrical devices such as motors or pumps, it issometimes necessary to bring the leads from the winding of the motorfrom a sealed oil filled cavity containing the motor to an adjacentisolated cavity wherein connections are made to an outlet cord andpossibly a pressure switch.

Past efforts to meet the sealing requirements have largely centeredaround three basic approaches all workable but possessing disadvantagesone of which being excessive costs. These current methods include (1)the use of the well known threaded compression screw to effect a seal tothe outer diameter of the lead which is emerging from a threaded hole inthe cavity, (2) the screwing down of a metal plate to compress afollower washer against a rubber ring seal which in turn compressesagainst the outer diameter of the lead and (3) the potting of an epoxyresin around the lead and bonding to the internal diameter of the holein the cavity.

The costs involved in using threaded components is obvious and isamplified by the assembly of multiple parts. Another disadvantage is theexcess of radially inward force due to the high mechanical advantage ofthe threads which sometimes create a thinning down of the leadinsulation to the point where it becomes susceptible to mechanicalabuse. Potting processes are at best inconvenient and often messycreating bottlenecks in high production assembly due to the need forapplication of heat and/or long cure times.

The present invention is intended to eliminate the aforementioneddisadvantages by using unique and simple means for effecting a suitableseal where it is required to bring the motor leads from an oil filledcavity into an adjacent cavity for making electrical connections.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a part sectional elevational view of a submersible pumpembodying the invention.

FIG. 2 is a fragmentary sectional exploded view on an enlarged scale ofa portion of the motor in FIG. 1.

FIG. 3 is a fragmentary sectional view on an enlarged scale of theportion of the motor shown in FIG. 2 showing the parts in assembledcondition.

DESCRIPTION

Referring to FIG. 1, the invention relates to submersible motors such asshown in FIG. 1 wherein a first frame or housing 10 comprising twohalves which enclosed the field stator 11 and rotor 12 on shaft 13, thatmay operate a pump impeller or the like. The interior of housing 10 ispreferably filled with oil and appropriate oil seals 14 are providedbetween the housing 10 and shaft 13.

A second housing 15 is removably mounted on housing 10 by screws 16.Housing 15 has a cavity in which electrical connections are made betweenthe leads from the motor housing 10 and a jacketed outlet cord 17 thatis connected to a power source. In addition, the cavity of secondhousing may include a pressure switch, not shown, to which connectionsare made from the motor winding and cord 17.

The housings 10, 15 are preferably made of a water and heat resistantdimensionally stable material such as powdered iron or a glassreinforced styrene modified polyphenylene oxide sold under the trademarkNORYL.

It is necessary to provide a seal between the ground wire 19 and thelead 18 extending from the motor winding 9 into the cavity of thehousing 15. (FIG. 3)

Referring to FIGS. 2 and 3, housing 10 includes an open endedcylindrical cavity 20 in the periphery of the housing 10 in which theopen end of the cavity 20 extends outwardly. A body or seal 21 ofresilient compressible elastomeric material is positioned in cavity 20.The body is preferably made of acrylonitrile-butadiene rubber sold underthe trademark BUNA N and having a shore durometer of 35 to 60 on the Ascale so that it falls within the qualifications of soft rubber.Satisfactory results have been achieved with a rubber having a durometerof 50.

The body 21 has axial passages 22 through which the wires 18, 19 extend.The second housing 15 includes an annular wall or projection 24 thatextends axially inwardly against the body 21. The body 21 is preferablycylindrical. The wires 18, 19 are unencased, that is they do not have acovering. The wires 18 from the motor winding are coated, for example,with a modified polyester and nylon films on the order of severalthousandths of an inch in thickness such as conventionally found on filminsulated copper or aluminum magnet wire used in the manufacture ofelectric motors. The ground wire 19 can be bare or similarly filminsulated but in any case is unencased.

The body 25 is slightly less than the diameter of the cavity 20 so thatthe body 21 can be readily inserted in the cavity 20. In addition thediameter of the passages or openings 22 is slightly greater than thediameter of the unencased wires 18, 19, so that the wires 18, 19 can bereadily inserted through passages 22. The passages 22 preferably have adiameter of between 100 and 130% of the diameter of wires 18, 19.

Initially, wires 18, 19 are passed through an opening 27 insertedthrough passages 22 and the body 21 is placed in cavity 20.

The housing 15 is then brought into position adjacent housing 10 so thatthe tubular projection 24 extends into cavity 20. As screws 16 aretightened, the tubular projection 24 compresses the body 21 axially andradially to provide a seal between the periphery of the cavity 20 andthe body 21 as well as between the wires 18, 19 and the body 21.

In the final assembled position, the housings 10, 15 are in abuttingcontact.

We claim:
 1. In a submersible motor or the like, the combinationcomprisinga first housing containing a motor field stator having a fieldwinding, a second plastic housing mounted on said first housing, saidfield having unencased field winding wires, said first housing having anopen ended cylindrical cavity therein in the periphery thereof with theopen end of said cavity extending outwardly of said housing, said firsthousing having a opening in the base of said cavity of lesser diameterthan said cavity, a cylindrical body of compressible elastomericmaterial positioned in said cavity, said body having an exteriorconfiguration and dimensions which conform generally with theconfiguration and dimensions of the cavity so that said body can bereadily inserted in said cavity without substantial compression, saidbody having a plurality of generally axial passages therein, saidunencased wires from said field winding having a diameter such that theycan be readily inserted through said passages when said body is radiallyuncompressed, said second housing having a cylindrical tubular wallhaving a uniform thickness and extending axially into the open end ofsaid cavity and has a radial end surface, and mounting means formounting said second housing on said first housing and drawing saidhousings toward one another to force said tubular wall axially againstsaid body to compress said body when said second housing is in mountedposition on said first housing thereby compressing said body radiallyoutwardly into tight conformity with the periphery of the cavity andradially inwardly into tight conformity with the unencased wires fromthe motor, the portion of said body radially inwardly of said tubularwall being unrestrained axially.
 2. The combination set forth in claim 1wherein said body has a shore hardness of about 35 to 60 on the A scale.3. The combination set forth in claim 2 wherein the diameter of theaxial passages in said body ranges between about 100% and 130% of thediameter of the unencased wires.